In communication technology, it is critically important to tune an antenna structure to a frequency. In the event of incorrect tuning, communication may be prevented, for example, or the communication range may be greatly reduced owing to a lack of signal injection.
RFID communication technology is a wireless communication technology designed for short ranges (“proximity” or “Near Field Communication”, NFC) or longer ranges (“long-range”). In this case, so-called RFID chips (“Radio Frequency IDentification”) are often used. RFID communication technology is used, for example, in smartcards, payment systems, smartphones and in logistics.
In RFID communication technology, incorrect tuning may result in coupling-in of energy, for example into an RFID chip, being reduced to such an extent that an RFID communication circuit cannot be activated at all in the first place.
The transmission of data and energy according to RFID communication technology can be implemented, for example, using electromagnetic waves (in “long-range” applications) and/or using electromagnetic fields, for example using magnetic induction (in “proximity” or “NFC” applications).
In order to tune an antenna structure of an RFID communication circuit, an RFID communication circuit usually detects electromagnetic waves or fields. The RFID communication circuit then changes from an energy-saving mode to a communication mode. The antenna structure is then electrically tuned to the frequency of the electromagnetic waves or fields using a variable component.
Furthermore, an irreversible technology is also conventionally used. For example, an RFID communication circuit can be retuned by interruptions in electrically conductive connections (for example established by means of a laser) or by so-called “e-fuses” by irreversibly changing one or more properties of an electronic component. However, such tuning can no longer be changed or optimized or can be changed or optimized at least only to a reduced extent.
For example, during communication between a reader and an RFID communication circuit using electromagnetic waves or fields, the antenna structure of the RFID communication circuit cannot be tuned to the frequency of the electromagnetic waves or fields before the start of communication. When communication begins, the passive RFID communication circuit obtains energy from the electromagnetic waves or fields in order to activate at least parts of the passive RFID communication circuit in order to tune the antenna structure. That is to say, at the start of communication, it may be necessary to couple in sufficient energy using a possibly incorrectly tuned antenna structure in order to enable tuning to a target frequency. This may mean, for example, that communication cannot be initiated or can be initiated only with a short range.